<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body {
            display: flex;
            width: 400px;
        }

        .a {
            width: 200px;
            height: 300px;
            border: 1px solid #000;
            flex-shrink: 0;
        }

        .b {
            /* width: 200%; */
            height: 400px;
            border: 1px solid #000;
        }
    </style>
</head>

<body>
    <div class="a"></div>
    <div class="b">啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊啊</div>


</body>

</html>